A sugar tax would provide the most health benefits to low income groups without excessively punishing them in the hip pocket, Australian researchers say.
In-depth economic analysis of a 20 per cent tax on sweetened beverages conducted at Deakin University's Global Obesity Centre found that the lowest socio-economic groups would only contribute $5 per year, or 10 cents a week, more in tax compared to wealthier groups.
Lead author Anita Lal, a PhD candidate in Deakin's School of Health and Social Development, says the finding debunks one of the major criticisms of a proposed sugar sweetened beverage tax - that it would unfairly target poorer families.
"We estimated the increase in annual spending on sugar sweetened beverages would be an average of $30 per person, or just 60 cents per week, a reasonable cost when the health benefits are taken into account," Ms Lal said.
While those in disadvantaged areas would pay slightly more tax, the difference was very small, Ms Lal said.
"The lowest groups would pay $35 per year and the highest groups would pay $30," she said.
The study published in journal PLOS Medicine looked at predicted changes in consumption levels due to a change in price, then converted that to a change in population body mass index, which helped predict the reduction in the prevalence of certain diseases related to obesity.
"Things like heart disease, some types of cancers and diabetes would be reduced as a result of a reduction in BMI and these are then converted to life years saved," Ms Lal told AAP.
The report also found a sugar tax could save $1.73 billion in healthcare costs over the lifetime of the population, and annual tax revenue was estimated at $642.9 million.
Ms Lal says a sugar tax isn't going to solve obesity on its own but it is an important part of the solution.
"It's about making the healthy choice, the easier and more affordable choice."
Research supervisor Professor Anna Peeters says the equity of the tax could be even further improved if the government revenue was used to fund initiatives benefiting those with greater disadvantage.
"In Australia right now almost two in three adults are overweight or obese, and a quarter of all children," Prof Peeters said.
She says something has to be done.
"A sugar sweetened beverage tax has been in place in Mexico for two years, and a drop in sales has been observed over the same period," she said.
"They've also seen the biggest drop in consumption in their most disadvantaged groups."